Safety device for paper pulp extractors



April 4, 1933. REESE r AL I 1,903,367

SAFETY DEVICE FOR PAPER PULP EXTRACTORS Filed Feb. 24. 19:51

INVENTCRS ZL'Ml/[L R5555 Z GEO/P65 Nib/W50 Z I 4 %TTORNEYS Patented Apr. 4, 1933 UNITED STATES, PATENT OFFI E LEMUEL v. REESE AND enoaen w. JOHNSON, or cINqIiinATI, orno; Assreuoas To im:

AMERICAN LAUNDRY MACHINERY COMPANY, or CINCINNATI, OHIO, A coRroBA TION OF OHIO SAFETY nnvrcn r03 PAPER PULP ExrRAoToRs;

Application filed remarya, 1931. Serial No. 517,831

usually embody a rotatable basket having a solid wall with means provided thereon forv retarding the normal tendency of the pulp to flow upwardly as well as trapping the impurities of heavier specific gravity than the pulp, and a skimming ring that is employed for skimming ofl the lighter weight impurities forming the inner strata of the mass Within the basket, the purified pulp, made up of fibers and water only, forming the center strata and being delivered con tinuously into a volute as untreatedpulp is fed' into the basket. In the operation of such centrifugal apparatus, the machine is first started into operation and the valve controlling the feed nozzle for the paper pulp.

is opened to permit the pulp to be discharged into the interior of the basket when the basket has been brought up to a predetermined speed. This sudden discharge of pulp into the machine is apt to be dangerous due to the fact that the inlet valve may be opened prior to the time when the basket has reached a speed of rotation in excess of the critical speed of the machine, or, that speed i in which the greatest amount of vibration takes place. That is,'the pulp may beinjected into the basket during the time the basket is rotating at such criticalspeed,'in which event the precession of the spindle on which the basket is mounted may be increased to such an extent that thebasket will strike the curb which may not only injure the machine but may also cause injury to the operator.

It is the object of our invention to provide a safety feature embodying an. automatic control means for governing the time of inlet for the supply of-pulp in which the inlet valve is automatically opened at a time when the machine reaches a predeter mined speed that is past the critical speed and-thereby render the inlet of pulp ineffective in increasing the precession spindle to' any harmful extent.

Various other objects and advantageous features of our invention may be seen in the following description and one embodiment thereof maybe seen in the accompanying drawing wherein similar characters of reference designate corresponding. parts and wherein the figure is a view partly in-section, partly in elevation, and partly diagrammatic showing acentrif'u'gal extractor with a control means constructed in accordance with our invention applied thereto.

Referring to the drawing, we have shown a centrifugal extractor consisting. of the usual curb 1 supported by suitable base members 2 and adapted to receive'a rotat; able basket 3, provided with suitable circum ferential baflle flanges 4 for retarding the upward flow of pulp and also for building up ,of the a pulp mat into which the heavy impurities extracted from the pulp duringthe centrifugal operation of the basket willbe imbedded,

a skimmer ring 5 and a filter means 6 adapted to filter out and retain thelighter ims purities within the basket while the liquid .is extracted therefrom by the centrifugal operation of the basket and passes over into. a volute 7 with the purified paper pulp from the basket. The basket 3 is mountedlon a suitable spindle 8 connected to the drive shaft :9 ofa motor or power. unit 10 pivotally mounted in a gimbal ring 11, that is, in turn,pivota1ly'. supported in suitable. uprights 12.. The lowermost end of' the spindle 8. rotates inv a bearing 13 carried by thecurb 1, thislbearw ing being of a wabble type which will permit of some free precessionaof the-spindlev and basket. An inlet pipe, 14 provides a, means. for delivering untreated pu ae the basket and this inlet pipe is under the controlof a; valve,15 which is, in turn}; controlled or operated by a solenoid operating means 16.

In accordance with our invention, an automatic valve operating means including the motor or power unit 10, suitable contactor coils, and the solenoid valve operating means 16 is provided for causing operation of the valve 15 .to open the same at a time when the basket 3 is rotating at a speed greater than the critical speed by delaying operation of the solenoid valve operatingvmeans 16. This operating and control means can best be described and understood by describing it as when in operation. 1

To start the machine in operation, the operator closes starting switch 17 whereupon a contactor coil 18 is energized through the following circuit: 3 s

From L3 through line 19, relay coil 20, line 21', contactor coil 18, line 22, stop switch 23 that is normally in closed position as shown,.and held closed by a spring 23, line 24, starting switch 17 line 25 to L2. The apparatus is so constructed that it is necessary for the operator to hold the starting switch 17 in closed position until the basket attains and passes the critical speed of rotation and reaches the predetermined speed at which time the pulp can be admitted to the basket 3 with safety by opening the valve 15 whereupon the valve 15 is opened by the automatic operation of the solenoid valve operating means. in the manner hereinafter described and at which time the starting switch 17 need no longer'be held in closed position.

The instant contact coil 18 is energized, this closes the'circuit through motor 10 and the inertia of the mass, comprising the rotatable portions of the .machine and motor, causes an abnormally high current to pass from the service lines to the motor which current rapidly decreases as the mass accelcrates and passes the critical speed.

Obviously, with the means hereinafter described for preventing the opening of the inlet valve 15 until the motor and mass have passed through the critical speed and the current reduced to a corresponding value the time at which the valve will open is predetermined with reference to the speed of the mass and where the statement predetermined speed hereafter is used, it is to be understood as being reached when the current value decreases to the extent which permits the valve to open.

' It is further obvious that until the mass has accelerated to and passed through the critical speed, the current value will not decrease sufliciently to establish the electrical circuit through which the'valve is actuated, thus automatically insuring that the mass will have passedthrough the critical speed before the valve opens.

Energization of the contactor coil 18 causes contacts 18a and 18b to close and thus comlete the following motor circuits; one, from 1 through the line 26, contact 186, line 27 to motor terminal T1; two, from line L2 to line 28, contact 180;, line 29 to motor terminal T2; three, from L3 to line 19, relay coil 20, line 30, to motor terminal T3. The completion of the above three circuits will cause the motor 10 to operate.

The abnormal high value of'the current passingthrough from L3 to motor terminal T3 at the instant the motor starts. causes a relatively abnormal increase in the lines of force through relay coil 20 .as a result} of which the relay switch 20a opens and maintains open as long as this abnormal current persists. Thisrelay switch 20a is a normally closed device and completes the circuit through which the contactor coil 18 is maintained energized as well as completing the circuit through which the solenoid coil 16 for the actuation of the valve is energized. Therefore, until this relay switch 20a recloses, thesolenoid coil 16 will not be energized and in addition, the operator must maintain the start button 17 in contact by maintainingthis button depressed.

As the current passing through this relay coil 20 decreases the lines of force tend-v ing to keep the relay switch 20a open will lessen in value until such time as the pull.

exerted by the lines of force are less than enough to overcome the normally closed bias of the switch at which time the switch recloses and the valve solenoid 16 will be energized opening the valve and the operator may now release the start button.

The maintaining circuit for contactor coil 18 isthen made from L2, through line 28, contact 18a, contact 180, which is closed simultaneously with the closing ofthe contacts 18a and 186, line 31, relay switch 20a, line 32, stop switch 23, line 22, contactor coil 18, line 21, relay coil 20, line 19, to L3.

The circuit to the solenoid valve 16 is from, L2, line 28, contact 18a, contact 180, line 31, relay contact 20a, arm 20?), line 33, solenoid 16, line 34, line 19 to L3.

The control arrangement is such that when the above circuit is completed through the solenoid 16 and the basket 3 has reached pre-' determined speed above the critical speed at which time the pulp can be safely admitted without causing dangerous precession of the spindle and basket.

Due to the holding circuit, the valve 15 will remain in open position until itisdesired to stop the machine at which time the stop switch 23 is depressed breaking the holding circuit for the coil 18 and also the hold-- ing circuit for the solenoid 16 and the valve 15 will automatically close cutting off the supply of pulp to the machine.

On de-energization of the solenoid 16 in this manner the valve 15 will remain in closed position until the machine is restarted and again reaches the predetermined speed as hereinbefore described. 7 i

With the above construction, we have provided a control mechanism for a centrifugal extracting apparatus as used in the purification of paper pulp wherein the danger normally inherent in a machine with no means for preventing inlet of paper pulp into the basket while the machine is driven at a critical speed is eliminated. In other words, we have provided a control apparatus that will automatically open the inlet for paper pulp into the machine when the macine has reached a predetermined speed only and not before the attainment of such speed. The control mechanism is of a nature to be dependent on the inrush of current and speed of operation of the motor means or power unit for automatic operation of the inlet valve to admit paper pulp to the basket. With such construction, possibility of admission of pulp to the basket when the basket is operating at critical speed is eliminated.

What we claim is:

1. A centrifugal extractorfor liquid materials comprising, a rotatable basket, a driv-' ing motor therefor, a normally closed valve controlling the supply of liquid material to the basket, controlling and operating means for said motor including a device sensitive to variations in motor speed during its acceleration, and connections therefromto said valve arranged to open the same when the motor speed reaches a predetermined value.

2. A centrifugal extractor for liquid materials comprising, a rotatable basket, a driving motor therefor, a normally closed valve controlling the supply of liquid material to the basket, controlling and operating means for said motor including a starting relay and circuit, a maintaining circuit for said relay, a device sensitive to variations in the motor speed during its acceleration, and connections therefrom to said valve arranged to open the same when the motor speed reaches a predetermined value.

3. A centrifugal extractor for liquid materials comprising, a rotatable basket, a driving motor therefor, a normally closed valve controlling the supply of liquid material to the basket, controlling and operating means for said motor including a starting relay and circuit, a maintaining circuit for said relay, a

device sensitive to variations in motor speed during its acceleration, and means controlled thereby arranged to open said Valve and to complete said maintaining circuit when the motor speed reaches a predetermined value.

4. A centrifugal extractor for liquid ma terials comprising, a rotatable basket, a driving motor therefor, a normally closed valve controlling the supply of liquid materials to the basket, controlling and operating means for said motor including a motor circuit, a device controlled by said circuit and sensitive to variations in motor speed during its acceleration, and connections therefrom to said valve arranged to open the same when the motor speed reaches a predetermined value.

5. A centrifugal extractor for liquid materials comprising, a rotatable basket, a driving motor therefor, a normally closed valve controlling the supply'of liquid material to the basket, controlling and operating means for said motor includinga motor circuit, a starting relay and circuit, a maintalning circuit for said relay, a device controlled by said motor circuit and sensitive to variations in motor speed during its acceleration, and means controlled thereby arranged to open said valve and to complete said maintaining circuit when the motor speed reaches a predetermined value.

In testimony whereof wehereby affix our signatures.

LEMUEL V. REESE. GEORGE W. JOHNSON. 

